This study compared the nutritional and psychological status of 855 pregnant adolescents and non-adolescents and assessed their relationships at three interviews (gestational age < or = 16 weeks, 20-26 weeks, and 30-36 weeks). The instruments used were: anthropometry, state-trait anxiety inventories (STAI), general health questionnaire (GHQ), and perceived stress scale (PSS). More adolescents were thinner, had higher scores of the trait anxiety inventory (TAI), wished to abort their children, and were worried about changes in their bodies than non-adolescents. Multiple linear regression analyses (controlling for toxic exposure, socioeconomic, demographic and obstetric factors) detected negative associations between weight gain in the first interview and distress (GHQ) for both the groups of women and weight gain in the second interview and the variable "worry about body's change" for the non-adolescent group. The negative associations between body mass index and chronic anxiety (TAI) were present in the three interviews for non-adolescents. This study detected a relationship between the nutritional and the psychological status of pregnant women, although there were more associations for non-adolescents.